O'Hare UFO sighting in 2006 one of the most famous reported

The city of Chicago isn’t known as a hotbed of UFO activity, but O’Hare Airport is the home of one of the most publicized sightings of the last decade.

A “flying saucer-like object” was spotted over Concourse C of the United terminal in November 2006 by pilots, airline management and mechanics. The incident, reported by a Chicago Tribune columnist a few weeks later, noted the object was first seen by a United ramp worker around 4:30 p.m.. After that, a variety of witnesses said the object was dark gray and 6 to 24 feet in diameter. Some said it appeared as a spinning Frisbee while others said it wasn’t rotating at all. All agreed the object was silent and appeared just below the 1,900-foot cloud deck, until shooting off into the clouds and leaving a circular hole shape in the clouds.

"But I know that what I saw and what a lot of other people saw stood out very clearly, and it definitely was not an [Earth] aircraft," one mechanic told reporter Jon Hilkevitch.

A manager on Concourse B ran outside his office after hearing the report about the sighting on an internal airline radio frequency.

"I knew no one would make a false call like that. But if somebody was bouncing a weather balloon or something else over O'Hare, we had to stop it because it was in very close proximity to our flight operations."

The story was eventually picked up by many major media outlets, and caused people to reconsider the idea of UFOs, though the Federal Aviation Administration and the airline refused to investigate the incident.

The FAA dismissed the incident as a weather phenomena and Dr. Mark Hammergren, an astronomer at Adler Planetarium, agreed, saying the weather conditions at O’Hare that day were right for a “hole-punch cloud.”

“It’s something that occurs when a propeller or jet airplane passes through when you have uniform cloud cover and the temperature is right near the freezing point,” Hammergren explained. “ They make liquid water droplets freeze and a hazy disc of ice crystals descends from a hole, and it looks like a perfect hole punched in the cloud.”

But for Center for UFO Studies Scientific Director Mark Rodeghier, the possible alien craft that appeared in the center’s own proverbial backyard remains a mystery worth exploring.

“It’s an unknown object over O’Hare, and it’s seen by official personnel, and does United or the FAA take it seriously? Of course not, they have zero interest because UFOs can’t exist. But how can you not worry about something hovering over an airport after 9/11? It doesn’t make sense,” Rodeghier said.

Journalist Leslie Kean also wrote about it in her book “UFOs: Generals, Pilots and Government Officials Go On The Record” and talked about in on “The Colbert Report” with Stephen Colbert in 2010, saying the government should investigate the O’Hare incident.

"This thing was hovering over Chicago O'Hare Airport at rush hour," Kean said. "Lots of people saw it … the U.S. government never said a word."